The live attenuated intranasal flu vaccine is the preferred method of immunizing healthy children aged 2-8 years against seasonal influenza, a federal panel has recommended.
At a meeting of the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices, committee members unanimously agreed that healthy children with no contraindications should receive the quadrivalent live attenuated vaccine (LAIV) rather than an inactivated vaccine, provided that the LAIV is readily available.
"If the LAIV is not immediately available, [inactivated influenza vaccine (IIV)] should be used," the recommendation reads. "Vaccination should not be delayed in order to procure LAIV."
All children aged 6 months or older should receive influenza vaccine, according to the recommendation. "Influenza vaccine should not be delayed to procure a specific vaccine preparation if an appropriate one is already available."
The committee approved the recommendation after hearing an evidence review that found the LAIV to be "moderately" more effective for this age group than the inactivated vaccine was. Although the data are not plentiful, they suggest that it would probably prevent about 47 more lab-confirmed cases of flu per 1,000 children than the IIV, Dr. Lisa Grohskopf said
"The benefits appear to outweigh the potential harms, with modestly better efficacy," and no appreciable increase in adverse events associated with the live vaccine, said Dr. Grohskopf, who is a medical officer in the influenza division of the Centers for Disease Control and Prevention in Atlanta.
Her review was based on two studies – one published in 2006 and one in 2007. The earlier study was an open-label trial that randomized about 2,300 children aged 6-71 months to either the LAIV or an IIV. The much larger 2007 study randomized about 16,000 children aged 6-59 months to the two vaccine types or to matching placebos.
The pooled analysis was limited to healthy children aged 24-59 months who were without a history of asthma or wheezing. The primary endpoint of lab-confirmed influenza infection was significantly less likely among children who had received the LAIV (hazard ratio, 0.47). The secondary endpoint of influenza-associated otitis media was also significantly less likely to occur among those who got the LAIV (HR, 0.47).
Neither of the vaccines was associated with any medically significant wheezing or fever, Dr. Grohskopf said.
She also examined these same endpoints in children who had a history of wheezing or asthma. The LAIV significantly reduced the risk of lab-confirmed influenza in this group (HR, 0.53). There were no significantly increased risks of medically significant wheezing in the children, regardless of whether or not they had experienced wheezing within the past 12 months.
However, Dr. Grohskopf said, she and her colleagues didn’t feel that the studies were strong enough to make any initial recommendations to the committee about whether the LAIV could safely be used in children with a history of wheezing or asthma. The studies didn’t drill down into data on this group enough, and the data are now too old to be completely reliable for this population.
Asthma and wheezing are not strict contraindications to the LAIV, she said, but ACIP does not recommend it for children with those issues or for those with any chronic conditions that might predispose them to complications from the flu.
The committee also heard that the strains included in the 2014-2015 vaccine will be the same as last season’s. Because of this, children who received at least one dose of the 2013-2014 vaccine will only need one dose of this year’s vaccine to ensure immunity. "This is analogous to what happened in the 2011-2012 season, when the vaccine strains were unchanged from the previous season," Dr. Grohskopf said.
She also touched on the issue of cost. "We haven’t done a formal cost-effectiveness analysis," she said.
"It’s likely to be a very complex undertaking because of the large number of products out there. It will probably be a few years before that could be done."
The best estimates available now can be drawn from the 2013-2014 private sector costs associated with CDC’s Vaccines for Children program. "The cost of the LAIV intranasal vaccine is $22.70/dose, and for the inactivated vaccine, there is a broad range of variability, from $7.65-$14.81/dose for the trivalent to $14.90-$21.09/dose for the quadrivalent."
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